perf: recover lost files (locale_selector.dart, terminology.py, app_zh_hant.arb)

These files were accidentally omitted during cherry-pick workflow.
They were present in 639ef12 but dropped when switching to git apply workflow.

backend/src/core/divination/terminology.py

@@ -0,0 +1,50 @@
+"""简繁术语映射表。
+
+用于将简体中文术语转换为繁体中文版本。
+"""
+
+# 六亲简体 → 繁体
+LIU_QIN_HANT = {
+    "子孙": "子孫",
+    "妻财": "妻財",
+}
+
+# 六神简体 → 繁体（只有"龙"需要转换，其他单字简繁相同）
+LIU_SHOU_HANT = {
+    "龙": "龍",
+}
+
+# 卦名常见简体 → 繁体
+# 六十四卦中需要转换的字符：为→為、贲→賁、颐→頤、离→離、无→無、壮→壯、晋→晉
+GUA_NAME_HANT = {
+    "为": "為",
+    "贲": "賁",
+    "颐": "頤",
+    "离": "離",
+    "无": "無",
+    "壮": "壯",
+    "晋": "晉",
+}
+
+
+def to_hant(text: str, mapping: dict[str, str]) -> str:
+    """将文本中的字符根据映射表转换为繁体。"""
+    result = text
+    for simplified, traditional in mapping.items():
+        result = result.replace(simplified, traditional)
+    return result
+
+
+def liu_shou_to_hant(single_char: str) -> str:
+    """将六神单字转换为繁体。"""
+    return LIU_SHOU_HANT.get(single_char, single_char)
+
+
+def liu_qin_to_hant(relation: str) -> str:
+    """将六亲转换为繁体。"""
+    return to_hant(relation, LIU_QIN_HANT)
+
+
+def gua_name_to_hant(name: str) -> str:
+    """将卦名转换为繁体。"""
+    return to_hant(name, GUA_NAME_HANT)